1. Field Of The Invention
The invention relates to electrophotographic image copying machines and more particularly to predicting failure in the paper handling path thereof.
2. Description Of The Prior Art
Copiers electrophotographically reproduce on paper, images originally represented on paper documents, magnetic media, etc. The more complicated the copier, the more chance for failure during operation. When a high volume, communication-oriented copier fails, it is difficult to retrieve lost information. Therefore, prediction of when a copier is likely to fail is important to the orderly conduct of business.
Ideally, copiers signal when and why they will fail in time for operators to methodically end current jobs and call service personnel. In IBM TECHNICAL DISCLOSURE BULLETIN entitled "Method for Testing Optical Tachometers," by R. F. Farnsworth et al, March 1980, pages 4383-4385, degradation in a servo-system beyond prespecified acceptable criteria gives an "early warning" of failure. Patent application Ser. No. 118,953, entitled "Improved Error Logging for Automatic Apparatus" by S. T. Riddle et al, filed Feb. 6, 1980, now U.S. Pat. No. 4,339,657, and assigned to IBM Corporation, Armonk, N.Y., compares errors with a criterion and logs the results. U.K. Pat. No. 1,449,777 statistically analyzes accumulated error counts in a data system. U.S. Pat. No. 3,471,685 discloses statistical analysis of a moving sheet's properties. U.S. Pat. No. 4,310,237 adjusts a copier's exposure, compensate for variations from a design standard, in accordance with a stored array. However, the prior art does not disclose apparatus for predicting that a copier will fail, before it actually fails, by statistical analysis of signals at selected points within the copier.